Burner with electrodynamic flame position control system

ABSTRACT

A burner includes a flame position actuator configured to control a location at which a flame is held. Combustion supported at a first location corresponds to high fuel dilution. An electric charge is applied to the fuel stream. If electrical power is lost or removed, the flame is shifted to a location corresponding to a lower fuel dilution.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority benefit from U.S. Provisional Patent Application No. 61/725,095, entitled “FAIL-SAFE ELECTRODYNAMIC BURNER”, filed Nov. 12, 2012; and U.S. Provisional Patent Application No. 61/717,371, entitled “LIFTED FLAME FAIL-SAFE LOW NOx BURNER”, filed Oct. 23, 2012; and U.S. Provisional Patent Application No. 61/727,103, entitled “SYSTEM FOR SAFE POWER LOSS FOR AN ELECTRODYNAMIC BURNER”, filed Nov. 15, 2012; and U.S. Provisional Patent Application No. 61/765,022, entitled “PERFORATED FLAME HOLDER AND BURNER INCLUDING A PERFORATED FLAME HOLDER”, filed Feb. 14, 2013; and U.S. Provisional Patent Application No. 61/882,201, entitled “COMBUSTION SYSTEM AND METHOD FOR ELECTRICALLY ASSISTED START-UP”, filed May 10, 2013; each of which, to the extent not inconsistent with the disclosure herein, are incorporated by reference.

SUMMARY

According to an embodiment, a burner with electrodynamic flame position control system includes a charging mechanism configured to apply a charge or voltage to a flame or a fuel stream supporting the flame. A first flame support surface is disposed adjacent to or immersed in the fuel stream and configured to support the flame when the charge or voltage is applied to the flame or the fuel stream. The first flame support surface can be a perforated flame holder configured to support a low NOx flame in a plurality of gas passages formed to extend through the perforated flame holder. In another embodiment, one or more field electrodes are disposed to apply an electric field or second charges to the flame, the electric field or second charges being selected to enhance combustion of the flame. An aerodynamic flame holder is disposed separated from the fuel stream. A flame position actuator is configured to selectively engage the aerodynamic flame holder with the fuel stream when the charge or voltage is not applied to the flame or fuel stream.

According to an embodiment, a method for supporting a flame includes applying a charge or voltage to a fuel stream or a flame supported by the fuel stream, causing the fuel stream to flow along a path separated from an aerodynamic flame holder at a second location, and supporting the flame with the fuel stream at a first location. Application of the charge or voltage to the fuel stream or the flame is stopped. When the application of the charge or voltage to the fuel stream or the flame is stopped, a flame position actuator is operated to cause the fuel stream to flow along a path adjacent to the aerodynamic flame holder. The flame is shifted from the first location to a second location and supported at the second location.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram of a burner with electrodynamic flame position control system, according to an embodiment.

FIG. 1B is a diagram of the burner with electrodynamic flame position control system of FIG. 1A, with no charge applied to the flame or fuel stream, according to an embodiment.

FIG. 2 is a diagram of a burner with electrodynamic flame position control system, according to another embodiment.

FIG. 3A is a diagram of a burner with electrodynamic flame position control system with a fuel nozzle actuator, according to an embodiment.

FIG. 3B is a diagram of the burner with electrodynamic flame position control system of FIG. 3A with no charge applied to the flame or fuel stream, according to an embodiment.

FIG. 4 is a flow chart showing a method for operating a burner with electrodynamic flame position control system, according to an embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Other embodiments may be used and/or other changes may be made without departing from the spirit or scope of the disclosure.

FIG. 1A is a diagram of a burner with electrodynamic flame position control system 100, according to an embodiment. A charging mechanism 104 is configured to apply a charge or voltage to a flame 102 or a fuel stream 106 supporting the flame. A first flame support surface 108 is disposed adjacent to the fuel stream 106. The first flame support surface 108 is configured to support the flame 102 when the charge or voltage is applied to the flame 102 or the fuel stream 106. An aerodynamic flame holder 110 is disposed away from the fuel stream 106. A flame position actuator 112 can be configured to selectively engage the aerodynamic flame holder 110 with the fuel stream 106. For example, the flame position actuator 112 can be configured to cause the aerodynamic flame holder 110 to support the flame 102 when the charge or voltage is not applied to the flame 102 or fuel stream 106.

The fuel stream 106 can include a diverging fuel stream 106 that becomes successively more dilute with distance from a fuel nozzle 114. The divergence of the stream typically corresponds to entrainment of air or flue gas 116 adjacent to the fuel stream 106. Accordingly, the term “fuel stream 106” can refer to substantially pure fuel (e.g., near the fuel nozzle 114) or to diluted fuel (e.g., away from the fuel nozzle 114).

The charging mechanism 104 can be disposed to apply a charge or voltage to the fuel stream 106 at various locations. For example, the charging mechanism 104 can be disposed to apply a charge or voltage to the fuel stream 106 between the aerodynamic flame holder 110 and the first flame support surface 108. Additionally or alternatively, the charging mechanism 104 can be disposed to apply a charge or voltage to the flame above the first flame support surface 108. Additionally or alternatively, the charging mechanism 104 can be disposed to apply a charge or voltage to the fuel stream below the aerodynamic flame holder 110.

The first flame support surface 108 can be disposed more distal from the fuel nozzle 114 than the aerodynamic flame holder 110. The first flame support surface 108 can be configured to support the flame at a distance from a fuel nozzle 114 corresponding to a reduced fuel concentration compared to the fuel concentration proximate the aerodynamic flame holder 110. The reduced fuel concentration at the distance from the fuel nozzle 114 corresponding to the first flame support surface 108 can correspond to a reduced production of oxides of nitrogen (NOx) compared to a higher fuel concentration flame 102 supported by the aerodynamic flame holder 110. The reduced fuel concentration at the distance from the fuel nozzle 114 corresponding to the first flame support surface 108 can correspond to a flame 102 that is unstable without the first flame support surface being sufficiently hot, sufficiently intact, or without the charge or voltage being applied to the flame 102 or fuel stream 106 by the charging mechanism 104 (and/or without field electrodes 120 influencing the flame 102) according to various embodiments.

The first flame support surface 108 can include a flame support electrode 108 configured to attract the charge or voltage applied to the flame 102 or fuel stream 106. The attraction of the charge or voltage applied to the flame 102 or fuel stream 106 by the flame support electrode 108 can cause the flame 102 to be supported by the flame support electrode 108. The flame support electrode can be held at voltage ground. Additionally or alternatively, a voltage source 118 can be operatively coupled to the flame support electrode and can be configured to drive the flame support electrode to a voltage opposite in sign from the polarity of the charge or voltage applied to the flame or fuel stream 106. The attraction of the charge or voltage applied to the flame 102 or fuel stream 106 can cause the flame to anchor to the flame support electrode 108.

According to embodiments, one or more field electrodes 120 can be operatively coupled to the voltage source 118. The one or more field electrodes 120 can be disposed to apply an electric field or second charges to the flame 102. The electric field or second charges can be selected to enhance combustion of the flame 102. Additionally or alternatively, the one or more field electrodes 120 can be configured to cause enhanced mixing of the fuel and an oxidizer to increase the stability of the flame 102 supported by diluted fuel.

According to embodiments, the voltage source 118 can be configured to drive the one or more field electrodes 120 with a steady or with a time-varying voltage. The one or more field electrodes 120 can be disposed more distal from a fuel nozzle 114 than the first flame support surface 108. The one or more field electrodes 120 can include one or more ion-ejecting electrodes. Additionally or alternatively, the one or more field electrodes 120 can include one or more dull electrodes configured to apply an electric field to the flame 102 and not eject ions. For example, one or more dull electrodes can include a toric electrode, as depicted in FIG. 1A. the one or more field electrodes 120 can be configured to flatten the flame 102.

Various embodiments are contemplated for the voltage source 118. The voltage source can, for example, include a linear power supply, a switching power supply, and/or a voltage multiplier. In an embodiment, the voltage source 118 includes linear and switching (e.g. flyback) power supply sections that output a chopped signal to a voltage multiplier. For example, the power supply sections can output a chopped DC waveform at 0 to +12 volts. The voltage source 118 can include an 11-stage positive polarity voltage multiplier that receives the chopped DC waveform and multiplies it to about 24,000 volts for output to the charging mechanism 104. The voltage source 118 can also include one or more power supply sections that output a second chopped DC waveform at 0 to −12 volts. The voltage source 118 can include a second voltage multiplier, for example, a 10 stage negative polarity voltage multiplier that receives the second chopped DC waveform and multiplies it to about −12,000 volts for output to the flame support electrode 108.

According to embodiments, a voltage source 118 can be operatively coupled to the charging mechanism 104. The voltage source 118 can drive the charging mechanism 104 in various ways. For example, the charging mechanism 104 can impart a time-varying voltage onto the flame 102 or fuel stream 106. According to an embodiment, the charging mechanism 104 can impart a positive charge or voltage on the flame 102 or fuel stream 106.

The voltage source 118 can be configured to receive electrical power from an electrical power node 120 that is subject to loss of electrical power. Additionally or alternatively, the voltage source 118 can be subject to at least possible loss of operability for supplying electrical voltage to the charging mechanism 104. The charging mechanism 104 can be subject to at least possible loss of operability for applying the charge or voltage to the flame 102 or fuel stream 106 responsive to a loss of voltage received from the voltage source 118. The at least possible loss of operability for applying the charge or voltage to the flame 102 or fuel stream 106 by the charging mechanism 104 can correspond to at least a possible loss of flame 102 stability when the flame 102 is supported by the first flame support surface 108.

In an embodiment, the voltage source 118 can be operatively coupled to a control mechanism such as a microcontroller- or microprocessor-based circuit to cause voltage to be applied to or to be removed from the electrical power node 120. The controller can alternatively include a human interface configured to receive commands from a human operator. For example, the control mechanism can be configured to output commands corresponding to a start-up method wherein the flame 102 is supported at the second location to pre-heat the first flame support surface 108. In another example, the controller can include a sensor configured to sense an operating condition of the first flame support surface 108, and the controller can be configured to cause a removal of voltage from the electrical power node 120 if the operating condition of the first flame support surface 108 indicates a movement of the flame to the aerodynamic flame holder 110 (e.g., if the first flame support surface 108 becomes too cool or suffers a mechanical failure). In another example, the controller can be configured to cause a removal of voltage from the electrical power node 120 upon receipt of a shut-down or idle command (e.g., responsive to a reduction in heat demand).

According an embodiment, the charging mechanism 104 can include an ion-ejecting electrode. The ion-ejecting electrode can include a sharp electrode, such as a corona electrode, e.g., a serrated electrode. According to another embodiment, the charging mechanism 104 can include an ionizer. The ionizer can be configured to increase an ion concentration in the fuel stream 106. Additionally or alternatively, the ionizer can be configured to increase an ion concentration in a flue gas or air adjacent to the fuel stream 106. Additionally or alternatively, the ionizer can be configured to increase an ion concentration in the flame 102. According to an embodiment, the charging mechanism 104 can include a fuel nozzle 114 configured to eject ions into the fuel stream 106.

Interaction of the electric field or second charges generated by the one or more field electrodes 120 with the flame can enhance combustion. It was found that a flame burned more vigorously responsive to the application of a voltage to the field electrode(s) than without a voltage applied to the field electrode(s). Loss of voltage applied to the field electrode(s) can result in a reduced combustion reaction rate, and hence a reduced flame stability. By causing the flame to be anchored to the first flame support surface 108, e.g., either in the form of a flame support electrode or an aerodynamic flame support surface when the field electrode(s) are energized, the flame can output reduced NOx because of relatively greater fuel dilution at and above the first flame support surface 108. By causing the flame to anchor to the aerodynamic flame holder 110 if voltage fails to reach the field electrodes 120, the flame can continue to burn stably (albeit with higher NOx output) while continuing to support the flame 102 under the leaner conditions at the first flame support surface 108.

FIG. 1B is a diagram of the burner with electrodynamic flame position control system of FIG. 1A, in a configuration 101 corresponding to no charge applied to the flame 102 or fuel stream 106, according to an embodiment. The aerodynamic flame holder 110 can be configured to support the flame 102 at a more stable fuel dilution than a flame 102 supported by the first flame support surface 108.

Divergence of the fuel stream 106 corresponds to dilution of the fuel by entrainment of air and/or flue gas peripheral to the fuel stream 106. At distances along the fuel stream 106 near the fuel nozzle 114, little air or flue gas 116 is entrained, and the fuel stream 106 is “richer” and is less diluted. At distances along the fuel stream 106 more distal from the fuel nozzle 114, a greater amount of air or flue gas 116 is entrained, causing the fuel stream 106 to be “leaner” and more diluted. Less diluted flames can be relatively stable, but can suffer from high NOx production. More diluted flames can be characterized by low NOx production, but can suffer from being relatively unstable. According to embodiments described herein, a more dilute, lower NOx flame 102 can be stabilized by the application of electrical charge or voltage to a fuel stream 106. Loss of electrical power by the fuel stream 106 charging mechanism 104 can result in reduced flame 102 stability. According to embodiments, a fail-safe system can cause the flame to burn at a location along the fuel stream 106 that is richer and more stable, albeit with higher NOx production.

A flame position actuator 112 can be configured to cause the flame 102 to be positioned at the first flame support surface 108 when the charge or voltage is applied to the flame 102 or fuel stream 106, and to cause the flame 102 to be positioned at the aerodynamic flame holder 110 when the charge or voltage is not applied to the flame 102 or fuel stream 106. The flame position actuator 112 can be configured to automatically select the flame 102 position responsive to presence or absence of electrical power. Additionally or alternatively, the flame position actuator 112 can be configured to automatically select the flame 102 position responsive to presence or absence of charge or voltage applied to the flame 102 or fuel stream 106. The flame position actuator 112 can be configured to cause the fuel stream 106 to form one or more vortices 124 adjacent to the aerodynamic flame holder 110. Thus, the aerodynamic flame holder 110, can operate as a “bluff body” to anchor the flame 102.

Referring to FIGS. 1A, 1B, several approaches to making a flame position actuator 112 are contemplated. According to an embodiment, the flame position actuator 112 can include an aerodynamic flame holder 110 retractor. For example, the flame position actuator 112 can be configured to hold the aerodynamic flame holder 110 away from the fuel stream 106 when the charge or voltage is applied to the flame 102 or fuel stream 106. The flame position actuator 112 can be configured to hold the aerodynamic flame holder 110 away from the fuel stream 106 against a restoring force. The restoring force can remain coupled to the aerodynamic flame holder 110 even when the charge or voltage is not applied to the flame 102 or fuel stream 106. For example, the aerodynamic flame holder 110 can be positioned adjacent to or impinged by the fuel stream by the absence of a pressure or motive force applied by an electrically-operated device against the restoring force. The restoring force can be understood to provide thrust and movement to move the aerodynamic flame holder 110 against the fuel stream 106.

The flame position actuator 112 can be configured to hold the aerodynamic flame holder 110 away from the fuel stream 106 against a spring. Additionally or alternatively, the flame position actuator 112 can be configured to hold the aerodynamic flame holder 110 away from the fuel stream 106 against gravity. Additionally or alternatively, the flame position actuator 112 can be configured to hold the aerodynamic flame holder 110 away from the fuel stream 106 against a pneumatic force. With proper pressure regulation, e.g., using an encoder to control pressure as a function of position, a hydraulic system can provide the restoring force. It may be advantageous to ensure that any restoring force pressure regulation subsystem is operable even in the absence of electrical power.

Various driving technologies for pushing against the restoring force are contemplated. According to an embodiment, the flame position actuator 112 can include an electrostatic retractor operatively coupled to the aerodynamic flame holder 110. Additionally or alternatively, the flame position actuator 112 can include an electromagnetic retractor operatively coupled to the aerodynamic flame holder 110. Additionally or alternatively, the flame position actuator 112 can include a pneumatic or hydraulic retractor operatively coupled to the aerodynamic flame holder 110.

FIG. 2 is a diagram of a burner with electrodynamic flame position control system 200, according to another embodiment wherein the flame position actuator 112 includes a fuel stream 106 deflector configured to cause the fuel stream 106 to deflect away from the aerodynamic flame holder 110 when the voltage is applied to the flame 102 or fuel stream 106. The fuel stream deflector can exert a force 202 on the fuel stream 106 to cause the fuel stream 106 to not form a vortex adjacent to the aerodynamic flame holder.

According to an embodiment, the flame position actuator 112 can include an ionic wind fuel stream deflector. The ionic wind fuel stream deflector can form at least a portion of the charging mechanism 104. The fuel stream 106 can be charged by such an ionic wind fuel stream deflector. Additionally or alternatively, the flame position actuator 112 can include a pressurized fluid fuel stream deflector. For example, the pressurized fluid (e.g., gas) can blow at an acute or oblique angle against the fuel stream 106. According to embodiments, the pressurized fluid can include flue gas or air 116.

FIG. 3A is a diagram of a burner with electrodynamic flame position control system 300 having a flame position actuator including a fuel nozzle actuator 302, according to an embodiment. FIG. 3B is a diagram of the burner with electrodynamic flame position control system of FIG. 3A in a state 301 corresponding to no charge applied to the flame 102 or fuel stream 106, according to an embodiment. A fuel nozzle actuator 302 can be configured to position the fuel nozzle 114 in a first fuel nozzle position 304 aligned to cause the fuel stream 106 to bypass the aerodynamic flame holder 110 when charge is applied to the flame 102 or fuel stream 106. Referring to FIG. 3B, the fuel nozzle actuator 302 can be configured to position the fuel nozzle 114 in a second fuel nozzle position 304 aligned to cause the fuel stream 106 to form a vortex 124 adjacent to the aerodynamic flame holder 110 when no charge is applied to the flame 102 or fuel stream 106. The fuel nozzle actuator 112 can include a fuel nozzle angle actuator 112. Additionally or alternatively, the fuel nozzle actuator 302 can include lateral position actuator and/or nozzle extension actuator. In another embodiment, the fuel nozzle actuator 302 can include a variable fuel aperture configured to select a divergence angle of the fuel stream 106. In another embodiment, the fuel nozzle actuator 302 can include an oscillating tip driving to vibrate between two or more locations selected to substantially avoid fuel stream 106 impact onto the aerodynamic flame holder 110 when power is applied to the fuel nozzle actuator and objectively to any and all necessary corresponding systems. According to an embodiment, the flame position actuator 112 can include a fuel stream 106 guidance vane or other apparatus configured to control fuel streaming post fuel nozzle 114 exit.

FIG. 4 is a flow chart showing a method 400 for operating a burner with electrodynamic flame position control system, according to an embodiment. The method 400 can be regarded as representing two operating states. In the first operating state (represented by 422, 404 (424), 426, 406, 408 (402), and including the loop from 406 through 410) corresponds to a “normal” operating state while the electrodynamic system is in operation. A second operating state (represented by 412, 414, 416, and 418 looping through 420) can correspond to a power up procedure, power down procedure, a diagnostic procedure, or a power failure event, for example. That is, in the second operating state, the electrodynamic system is not in operation.

In an operation 402, a charge or voltage is applied or imparted (on) to a fuel stream or a flame supported by the fuel stream. Operation 402 can thus represent operation of an electrodynamic system. Applying a charge or voltage to the fuel stream or flame in operation 402 can include imparting a time varying charge or voltage or a positive charge or voltage on the fuel stream or flame. Additionally or alternatively, operation 402 can include ejecting charge from at least one sharp or corona electrode. Ejecting charge from at least one sharp or corona electrode can include ejecting charge from at least one serrated electrode.

According to various embodiments, operation 402 can include applying a charge or voltage to the fuel stream or flame with a conductive fuel nozzle. Additionally or alternatively, operation 402 can include operating an ionizer to supply ions to the fuel stream after exit of the fuel stream from a fuel nozzle. Additionally or alternatively, operation 402 can include operating an ionizer to ionize the fuel prior to exit of the fuel stream from a fuel nozzle. Additionally or alternatively, operation 402 can include operating an ionizer to ionize flue gas or air upstream from or peripheral to the fuel stream. Additionally or alternatively, operation 402 can include operating an ionizer or electrode to ionize the flame.

In operation 404, wherein the fuel stream is caused to flow along a path separated from an aerodynamic flame holder at a second location. According to an embodiment, causing the fuel stream to flow along a path separated from an aerodynamic flame holder in operation 404 can include operating a flame position actuator configured to hold the aerodynamic flame holder away from the fuel stream when the charge or voltage is applied to the flame or fuel stream. According to another embodiment, operation 404 can include operating a flame position actuator configured to hold the fuel stream away from the aerodynamic flame holder when the charge or voltage is applied to the flame or fuel stream.

As represented by operation 406, a flame is supported with the fuel stream at a first location. In embodiments, the first location can be regarded to correspond to the first flame support surface 108. Supporting the flame at a first location and can include supporting the flame with a first flame support surface at the first location disposed more distal from a fuel nozzle than the second location. Additionally or alternatively, operation 406 can include applying a voltage condition to a flame support electrode at the first location. Additionally or alternatively, operation 406 can include attracting the charge or voltage applied to the fuel stream or flame with the voltage condition applied to the flame support electrode. Additionally or alternatively, attracting the charge or voltage applied to fuel stream or flame with the voltage condition applied to the flame support electrode can cause the fuel stream to flow toward the flame support electrode. Applying the voltage condition to the flame support electrode can include holding the flame support electrode at voltage ground. Additionally or alternatively, applying the voltage condition to the flame support electrode can include applying a voltage opposite in sign from the charge or voltage applied to the fuel stream or flame. Additionally or alternatively, applying the voltage condition to the flame support electrode can cause the flame to anchor to the flame support electrode.

According to various embodiments, operation 406 can support the flame at the first location and can include supporting the flame with a first aerodynamic flame support surface disposed at the first location. Additionally or alternatively, operation 406 can include causing a vortex to form in the fuel stream proximate a first aerodynamic flame support surface disposed at the first location. The first aerodynamic flame support surface can include an electrically insulating material.

According to various embodiments, operation 406 can include supporting a lean, low oxides of nitrogen (NOx) flame a distance from a fuel nozzle corresponding to a reduced fuel concentration compared to a fuel concentration proximate to the second location. Operation 406 can include supporting a flame that is unstable without the charge or voltage being applied to the fuel stream or flame. Additionally or alternatively, operation 406 can include supporting a flame that is unstable without a flame holder disposed at the first location being heated to a sufficiently high temperature (e.g., 1700° F.) to maintain combustion at the second location.

Proceeding to optional operation 408, an electric field is or second charges are applied to the flame with one or more field electrodes. The electric field or second charges can be selected to enhance combustion in the flame. Additionally or alternatively, the electric field or second charges can cause enhanced mixing of the fuel and an oxidizer that can increase the stability of the flame supported by diluted fuel stream. Applying an electric field or second charges to the flame with one or more field electrodes can correspond to application of a time-varying voltage to the one or more field electrodes, or can correspond to applying a substantially DC voltage to the one or more field electrodes.

According to various embodiments, operation 408 can include applying the electric field or second charges with one or more field electrodes disposed more distal from a fuel nozzle than the first location. The one or more field electrodes can include one or more ion-ejecting electrodes. Additionally or alternatively, the one or more field electrodes can include one or more dull electrodes that apply an electric field to the flame and not eject ions. The one or more field electrodes can include a toric electrode. According to an embodiment, applying an electric field or second charges to the flame with one or more field electrodes and can result in flattening the flame with the electric field.

While electrical power continues to be applied (as represented by the loop 410→406→408→410) generally along with continued execution of steps 402 and 404), the flame can continue to be supported at the first location while one or more field electrodes stabilize, maintain ignition, and/or otherwise affect combustion characteristics of the flame (step 408) or while a perforated flame holder stabilizes a flame at the first location. Applying an electric field or charge to the flame while the flame is at the first location in operation 408 can include applying an electric field selected to enhance combustion.

The system can continue to execute operations 402 through 410 indefinitely. At some point, electrical power can be interrupted and the decision operation 410 can cause the method 400 to proceed to operation 412. The interruption in electrical power can be related to a power failure, for example. Additionally or alternatively, the interruption in electrical power can be related to a power-up procedure, power down procedure, a failure of a flame holder at the first location, a diagnostic procedure, or other planned interruption in electrical power.

Upon execution of operation 412 e.g., simultaneously with or subsequent to operation 412, an operation 414 includes operation of a flame position actuator to cause the fuel stream to flow along a path adjacent to the aerodynamic flame holder. A path adjacent to the aerodynamic flame holder can include a fuel stream path that impacts at least partially upon the aerodynamic flame holder. Causing the fuel stream to flow along a path adjacent to an aerodynamic flame holder (e.g., “bluff body”) can tend to cause vortices to form along a lee side of the aerodynamic flame holder.

According to embodiments, operating the flame position actuator to cause the fuel stream to flow along a path adjacent to the aerodynamic flame holder in operation 414 can include actuating a movement of at least a portion of the aerodynamic flame holder. Actuating a movement of at least a portion of the aerodynamic flame holder can include ceasing to hold the aerodynamic flame holder away from the fuel stream against a restoring force that remains coupled to the aerodynamic flame holder when the charge or voltage is not applied to the flame or fuel stream. For example, actuating a movement of at least a portion of the aerodynamic flame holder in operation 414 can include ceasing to hold the aerodynamic flame holder or a linkage coupled to the aerodynamic flame holder against a pressure or weight. Additionally or alternatively, actuating a movement of at least a portion of the aerodynamic flame holder can include ceasing to hold the aerodynamic flame holder away from the fuel stream against a spring. Additionally or alternatively, actuating a movement of at least a portion of the aerodynamic flame holder can include ceasing to hold the aerodynamic flame holder away from the fuel stream against gravity. Additionally or alternatively, actuating a movement of at least a portion of the aerodynamic flame holder can include ceasing to hold the aerodynamic flame holder away from the fuel stream against a pneumatic or controlled hydraulic force.

Actuating a movement of at least a portion of the aerodynamic flame holder can include ceasing to operate an electrostatic retractor operatively coupled to the aerodynamic flame holder. Additionally or alternatively, actuating a movement of at least a portion of the aerodynamic flame holder can include ceasing to operate an electromagnetic retractor operatively coupled to the aerodynamic flame holder. Additionally or alternatively, actuating a movement of at least a portion of the aerodynamic flame holder can include ceasing to operate a pneumatic or hydraulic retractor operatively coupled to the aerodynamic flame holder.

In addition or alternative to moving the aerodynamic flame holder (e.g., “bluff body”), other approaches to operating a flame position actuator are contemplated. According to embodiments, operating the flame position actuator to cause the fuel stream to flow along a path adjacent to the aerodynamic flame holder in operation 414 can include actuating a movement of at least a portion of a fuel nozzle that provides the fuel stream. For example, operating the flame position actuator can include actuating a fuel nozzle position actuator. Actuating a movement of the fuel nozzle can include ceasing to hold the fuel nozzle or a linkage coupled to the fuel nozzle against a pressure or weight. Operating the flame position actuator can include operating a fuel nozzle angle actuator. Additionally or alternatively, operating the flame position actuator can include operating a fuel nozzle lateral position actuator. Additionally or alternatively, operating the flame position actuator can include operating a fuel nozzle extension actuator. Additionally or alternatively, operating the flame position actuator can include operating a fuel nozzle spray pattern actuator. Additionally or alternatively, operating the flame position actuator can include operating a cyclic fuel stream distribution actuator.

According to an embodiment, the flame holding first location and the second flame holding location can be substantially coextensive. Shifting the flame can consist essentially of changing a location of outflow of the fuel stream from the fuel nozzle. For example, the fuel nozzle can be moved to reduce fuel dilution when electrical energy is not applied to the flame or fuel stream.

Various embodiments of fuel nozzle actuators are contemplated. For example, actuating a movement of at least a portion of the fuel nozzle can include ceasing to operate an electrostatic holder operatively coupled to the fuel nozzle. Additionally or alternatively, actuating a movement of at least a portion of the fuel nozzle can include ceasing to operate an electromagnetic holder operatively coupled to the fuel nozzle. Additionally or alternatively, actuating a movement of at least a portion of the fuel nozzle can include ceasing to operate a pneumatic or hydraulic fuel nozzle holder operatively coupled to the fuel nozzle.

According to another embodiment, operating the flame position actuator to cause the fuel stream to flow along a path adjacent to the aerodynamic flame holder in operation 414 can include moving the fuel stream. For example, the flame position actuator can cease to deflect the fuel stream. For example, ceasing to deflect the fuel stream can include ceasing to operate an ionic wind fuel stream deflector. Additionally or alternatively, ceasing to deflect the fuel stream can include ceasing to operate a pressurized gas fuel stream deflector. Additionally or alternatively, ceasing to deflect the fuel stream can include ceasing to operate a fuel stream guidance vane.

Proceeding to operation 416, the flame is shifted from the first, electrodynamically stabilized, location to a second location corresponding to the aerodynamic flame holder. Shifting the flame from the first location to the second location can thus include forming a vortex adjacent to the aerodynamic flame holder. Forming a vortex adjacent to the aerodynamic flame holder can be selected to cause the flame to maintain ignition adjacent to the aerodynamic flame holder when no charge or voltage is applied to the fuel stream or flame. The flame can continue to be supported by the aerodynamic flame holder at the second position indefinitely while electrical power is not received, indicated by the loop between operation 418 and operation 420.

At some point, electrical power can be restored or can be turned on, at which time the decision operation 420 can cause the method 400 to proceed to operation 422. In operation 422, the application of the charge or voltage to the fuel stream or the flame and corresponding stabilization or enhancement of the flame resumes. Contemporaneously or subsequent to operation 422, in operation 424, the flame position actuator is operated to cause the fuel stream to flow along the path separated from the aerodynamic flame holder at the second position. The method 400 can include an operation 426 to shift the flame from the second location to the first location.

According to various embodiments, operation 422 that can resume the application of the charge or voltage to the fuel stream or the flame may occur responsive to 420 receiving electrical power. Proceeding to operation 426, which may occur simultaneously with operation 424, the flame can be shifted from the second location to the first location. Operation 424 can be performed by using the inverse of approaches described above in conjunction with operation 414. For example, rather than ceasing to press the aerodynamic flame holder against a restoring force, the flame position actuator can move the aerodynamic flame holder away from the fuel stream against the restoring force. Rather than ceasing to deflect the fuel stream away from the aerodynamic flame holder, the flame position actuator can cause the fuel stream to be deflected away from the aerodynamic flame holder. Rather than ceasing to hold the fuel nozzle against a restoring force, the flame position actuator can move the fuel nozzle against the restoring force.

In some embodiments, such as during a start-up procedure, the method 400 can begin with operation 418. For example, the method 400 can be at operation 418 fuel flow is established, while the flame is ignited, during warm-up from a cold start, etc.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. 

1. A burner with electrodynamic flame position control system, comprising: a charging mechanism configured to apply a charge or voltage to a flame or a fuel stream supporting the flame; a first flame support surface disposed adjacent to the fuel stream configured to support the flame when the charge or voltage is applied to the flame or the fuel stream; an aerodynamic flame holder disposed away from the fuel stream; and a flame position actuator configured to selectively engage the aerodynamic flame holder with the fuel stream to cause the aerodynamic flame holder to support the flame when the charge or voltage is not applied to the flame or fuel stream.
 2. The burner with electrodynamic flame position control system of claim 1, further comprising a fuel nozzle.
 3. The burner with electrodynamic flame position control system of claim 1, wherein the charging mechanism is disposed to apply a charge or voltage to the fuel stream between the aerodynamic flame holder and the first flame support surface.
 4. The burner with electrodynamic flame position control system of claim 1, wherein the charging mechanism is disposed to apply a charge or voltage to the flame above the first flame support surface.
 5. The burner with electrodynamic flame position control system of claim 1, wherein the charging mechanism is configured to impart a positive charge or voltage on the flame or fuel stream.
 6. The burner with electrodynamic flame position control system of claim 1, wherein the first flame support surface is disposed more distal from the fuel nozzle than the aerodynamic flame holder.
 7. The burner with electrodynamic flame position control system of claim 1, wherein the first flame support surface is configured to support the flame at a distance from a fuel nozzle corresponding to a reduced fuel concentration compared to the fuel concentration proximate the aerodynamic flame holder. 8.-9. (canceled)
 10. The burner with electrodynamic flame position control system of claim 7, wherein the first flame support surface includes a perforated flame holder configured to support a low NOx flame in a plurality of gas passages formed to extend through the perforated flame holder.
 11. (canceled)
 12. The burner with electrodynamic flame position control system of claim 1, wherein the first flame support surface includes a flame support electrode configured to attract the charge or voltage applied to the flame or fuel stream.
 13. The burner with electrodynamic flame position control system of claim 12, wherein the attraction of the charge or voltage applied to flame or fuel stream to the flame support electrode causes the flame to be supported by the flame support electrode.
 14. The burner with electrodynamic flame position control system of claim 12, wherein the flame support electrode is held at voltage ground.
 15. The burner with electrodynamic flame position control system of claim 12, further comprising a voltage source operatively coupled to the flame support electrode; wherein the voltage source is configured to drive the flame support electrode to a voltage opposite in sign from the charge or voltage applied to the flame or fuel stream.
 16. (canceled)
 17. The burner with electrodynamic flame position control system of claim 1, further comprising a voltage source; and one or more field electrodes operatively coupled to the voltage source and disposed to apply an electric field or second charges to the flame, the electric field or second charges being selected to enhance combustion of the flame. 18.-24. (canceled)
 25. The burner with electrodynamic flame position control system of claim 1, further comprising a voltage source operatively coupled to the charging mechanism. 26.-29. (canceled)
 30. The burner with electrodynamic flame position control system of claim 1, wherein the charging mechanism includes an ion-ejecting electrode. 31.-33. (canceled)
 34. The burner with electrodynamic flame position control system of claim 1, wherein the charging mechanism includes an ionizer. 35.-37. (canceled)
 38. The burner with electrodynamic flame position control system of claim 1, wherein the charging mechanism includes a fuel nozzle configured to eject ions into the fuel stream.
 39. The burner with electrodynamic flame position control system of claim 1, wherein the aerodynamic flame holder is configured to support the flame at a more stable fuel dilution than a flame supported by the first flame support surface.
 40. The burner with electrodynamic flame position control system of claim 1, wherein the flame position actuator is configured to cause the flame to be positioned at the first flame support surface when the charge or voltage is applied to the flame or fuel stream.
 41. The burner with electrodynamic flame position control system of claim 1, wherein the flame position actuator is configured to cause the flame to be positioned at the aerodynamic flame holder when the charge or voltage is not applied to the flame or fuel stream.
 42. The burner with electrodynamic flame position control system of claim 1, wherein the flame position actuator is configured to automatically select the flame position responsive to presence or absence of electrical power or absence of charge or voltage applied to the flame or fuel stream.
 43. (canceled)
 44. The burner with electrodynamic flame position control system of claim 1, wherein the flame position actuator includes an aerodynamic flame holder retractor.
 45. The burner with electrodynamic flame position control system of claim 44, wherein the flame position actuator is configured to hold the aerodynamic flame holder away from the fuel stream when the charge or voltage is applied to the flame or fuel stream; wherein the flame position actuator is configured to hold the aerodynamic flame holder away from the fuel stream against a restoring force that remains coupled to the aerodynamic flame holder when the charge or voltage is not tipped to the flame or fuel stream. 46.-52. (canceled)
 53. The burner with electrodynamic flame position control system of claim 1, wherein the flame position actuator includes a fuel stream deflector configured to cause the fuel stream to deflect away from the aerodynamic flame holder when the voltage is applied to the flame or fuel stream.
 54. The burner with electrodynamic flame position control system of claim 53, wherein the flame position actuator includes an ionic wind fuel stream deflector. 55.-62. (canceled)
 63. A method for supporting a flame, comprising: applying a charge or voltage to a fuel stream or a flame supported by the fuel stream; causing the fuel stream to flow along a path separated from an aerodynamic flame holder at a second location; supporting the flame with the fuel stream at a first location; stopping application of the charge or voltage to the fuel stream or the flame; operating a flame position actuator to cause the fuel stream to flow along a path adjacent to the aerodynamic flame holder; shifting the flame from the first location to a second location; and supporting the flame at the second location.
 64. The method for supporting a flame of claim 63, wherein causing the fuel stream to flow along a path separated from an aerodynamic flame holder includes operating a flame position actuator that is configured to hold the aerodynamic flame holder away from the fuel stream when the charge or voltage is applied to the flame or fuel stream.
 65. The method for supporting a flame of claim 63, wherein shifting the flame from the first location to the second location includes forming a vortex adjacent to the aerodynamic flame holder to cause the flame to maintain ignition adjacent to the aerodynamic flame holder when no charge or voltage is applied to the fuel stream or flame.
 66. (canceled)
 67. The method for supporting a flame of claim 63, further comprising: applying an electric field or charge to the flame while the flame is at the first location, the electric field being selected to enhance combustion.
 68. The method for supporting a flame of claim 63, further comprising: supporting a perforated flame holder at the first location to support a low NOx flame in a plurality of gas passages formed to extend through the perforated flame holder, and to supply heat to the fuel stream to maintain combustion.
 69. (canceled)
 70. The method for supporting a flame of claim 63, wherein operating the flame position actuator to cause the fuel stream to flow along a path adjacent to the aerodynamic flame holder includes actuating a movement of at least a portion of the aerodynamic flame holder. 71.-89. (canceled)
 90. The method for supporting a flame of claim 63, wherein operating the flame position actuator to cause the fuel stream to flow along a path adjacent to the aerodynamic flame holder includes stopping deflection of the fuel stream. 91.-93. (canceled)
 94. The method for supporting a flame of claim 63, further comprising: resuming the application of the charge or voltage to the fuel stream or the flame; operating the flame position actuator to cause the fuel stream to flow along the path separated from the aerodynamic flame holder at the second position; and shifting the flame from the second location to the first location. 95.-104. (canceled)
 105. The method for supporting a flame of claim 63, wherein supporting the flame at a first location includes supporting the flame with a first flame support surface at the first location disposed more distal from a fuel nozzle than the second location.
 106. The method for supporting a flame of claim 63, further comprising applying a voltage condition to a flame support electrode at the first location; and wherein supporting the flame at the first location includes attracting the charge or voltage applied to the fuel stream or flame with the voltage condition applied to the flame support electrode. 107.-113. (canceled)
 114. The method for supporting a flame of claim 63, wherein supporting the flame at a first location includes supporting a lean, low oxides of nitrogen (NOx) flame a distance from a fuel nozzle corresponding to a reduced fuel concentration compared to a fuel concentration proximate to the second location.
 115. (canceled)
 116. The method for supporting a flame of claim 63, further comprising, while the flame is supported at the first location, applying an electric field or second charges to the flame with one or more field electrodes, the electric field or second charges being selected to enhance combustion in the flame. 117.-123. (canceled) 